The U.S. Open began under partly cloudy skies on Thursday at challenging Oakmont Country Club where Bryson DeChambeau hopes to make a fast start to his title defence while tournament favourite Scottie Scheffler was hours from teeing off.

Even world No. 1 Scottie Scheffler knows he'll be at the mercy of Oakmont Country Club at the U.S. Open, a course he called "probably the hardest golf course that we'll play."

World number one Scottie Scheffler said Wednesday the formidable Oakmont course could provide "the hardest" challenge of his career at the 125th US Open this week.Second-ranked Rory McIlroy, who won the Masters in April to complete a career Grand Slam,

Seventy-two holes of struggle await the eventual 2025 U.S. Open winner as Oakmont Country Club is prepared to bare its teeth for a 156-man field all seeking to claim the national championship. The par-70 course is hosting the USGA's signature tournament and the third major championship of the season for a record 10th time with golfers attempting to transverse its difficult landscape for the first time in nine years.